Data source for parallel inference

ABSTRACT

Systems, methods, and other embodiments associated with data sources adapted for parallel inference on triples associated with a semantic model are described. One example method includes creating a source table that stores triples for entailment in a manner that is adapted for parallel inference. The source table may be partitioned by triple predicate or may store compact triple identifiers that have been mapped to triple identifiers from the semantic model.

BACKGROUND

The evolution of the web to a semantic web is gaining momentum. ResourceDescription Framework (RDF) is being widely adopted as a standard tocapture the semantics of data. Facts represented as RDF (subject,predicate, object) triples can capture both relationships betweenresources as well as attribute values associated with a resource. Aunique challenge of semantic data stores is the ability to automaticallyderive additional facts based on facts already asserted in the semanticmodel. These additional facts are derived using inference rules thatmodel the knowledge contained in the existing facts in a process calledentailment. With large semantic data models, firing the inference rulesto generate inferred triples is a processor-intense and time consumingprocess. For example, using a typical PC with 2.4 GHz processor, 8 GBmain memory and 3 TB in disk memory, firing approximately 50 inferencerules to entail the LUBM8000 ontology, a benchmark that includes morethan a billion triples, results in about 42 hours of processing timeusing Oracle Database 11.1.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate various example systems, methods,and other example embodiments of various aspects of the invention. Itwill be appreciated that the illustrated element boundaries (e.g.,boxes, groups of boxes, or other shapes) in the figures represent oneexample of the boundaries. One of ordinary skill in the art willappreciate that in some examples one element may be designed as multipleelements or that multiple elements may be designed as one element. Insome examples, an element shown as an internal component of anotherelement may be implemented as an external component and vice versa.Furthermore, elements may not be drawn to scale.

FIG. 1A illustrates an example embodiment of a system associated withserial inference.

FIG. 1B illustrates an example embodiment of a system associated withparallel inference.

FIG. 2 illustrates an example embodiment of a system associated withparallel inference.

FIG. 3 illustrates an example embodiment of a method associated withparallel inference.

FIG. 4 illustrates an example embodiment of a system associated withparallel inference.

FIG. 5 illustrates an example embodiment of a method associated withparallel inference.

FIG. 6 illustrates an example computing environment in which examplesystems and methods, and equivalents, may operate.

DETAILED DESCRIPTION

The entailment of a semantic data model involves firing a set ofinference rules on triples in the semantic data model to generateinferred triples. The rules are typically executed on a semantic modeltable that stores the triples associated with one or more semanticmodels. The semantic model table is usually partitioned by semanticmodel. Even when efforts are made to reduce the number of inferencerules, the entailment process is time consuming and requires largequantities of memory.

As part of the OWL 2 standardization effort led by the W3C, lessexpressive OWL rule subsets have been proposed that have polynomialcomplexity and are suitable for efficient and scalable reasoning overlarge datasets. One of these OWL subsets is OWL 2 RL, which is arule-based profile of OWL 2. Since it is described as a collection ofpositive Datalog rules, OWL 2 RL can be theoretically implemented on topof semantic stores that already provide rule-based reasoning. OWL 2 RLincludes a subset of inference rules that have been used in other modelsand also provides the capability for a user to add custom rules. Theserules include RDF constructs, inverse and functional properties,existential and value restrictions, and owl:intersectionOf.

One example technique for implementing an inference engine on suchsemantic data models is to pre-compute and materialize inferred triplesusing forward chaining, and later use the materialized view for queryanswering. The forward chaining approach repeatedly fires inferencerules on the corpus of asserted and inferred triples in the materializedview until no new facts can be inferred. Other inference techniquesapply inference rules at the time of query, which, while saving thememory used in generating inferred triples a priori, can significantlyslow query response time. While the pre-computing and materializing ofinferred triples will be discussed in the examples herein, it is to beunderstood that the methods and systems described herein may be appliedto any inference technique that involves entailment of a semantic datamodel by applying inference rules to a corpus of triples in the semanticdata model.

The following includes definitions of selected terms employed herein.The definitions include various examples and/or forms of components thatfall within the scope of a term and that may be used for implementation.The examples are not intended to be limiting. Both singular and pluralforms of terms may be within the definitions.

References to “one embodiment”, “an embodiment”, “one example”, “anexample”, and so on, indicate that the embodiment(s) or example(s) sodescribed may include a particular feature, structure, characteristic,property, element, or limitation, but that not every embodiment orexample necessarily includes that particular feature, structure,characteristic, property, element or limitation. Furthermore, repeateduse of the phrase “in one embodiment” does not necessarily refer to thesame embodiment, though it may.

“Computer-readable medium”, as used herein, refers to a medium thatstores signals, instructions and/or data. A computer-readable medium maytake forms, including, but not limited to, non-volatile media, andvolatile media. Non-volatile media may include, for example, opticaldisks, magnetic disks, and so on. Volatile media may include, forexample, semiconductor memories, dynamic memory, and so on. Common formsof a computer-readable medium may include, but are not limited to, afloppy disk, a flexible disk, a hard disk, a magnetic tape, othermagnetic medium, an ASIC, a CD, other optical medium, a RAM, a ROM, amemory chip or card, a memory stick, and other media from which acomputer, a processor or other electronic device can read.

In some examples, “database” is used to refer to a table. In otherexamples, “database” may be used to refer to a set of tables. In stillother examples, “database” may refer to a set of data stores and methodsfor accessing and/or manipulating those data stores.

“Data store”, as used herein, refers to a physical and/or logical entitythat can store data. A data store may be, for example, a database, atable, a file, a list, a queue, a heap, a memory, a register, and so on.In different examples, a data store may reside in one logical and/orphysical entity and/or may be distributed between two or more logicaland/or physical entities.

“Logic”, as used herein, includes but is not limited to hardware,firmware, software stored as computer executable instructions on acomputer-readable medium or in execution on a machine, and/orcombinations of each to perform a function(s) or an action(s), and/or tocause a function or action from another logic, method, and/or system.Logic may include a software controlled microprocessor, a discrete logic(e.g., ASIC), an analog circuit, a digital circuit, a programmed logicdevice, a memory device containing instructions, and so on. Logic mayinclude one or more gates, combinations of gates, or other circuitcomponents. Where multiple logical logics are described, it may bepossible to incorporate the multiple logical logics into one physicallogic. Similarly, where a single logical logic is described, it may bepossible to distribute that single logical logic between multiplephysical logics.

“Query”, as used herein, refers to a semantic construction thatfacilitates gathering and processing information. A query may beformulated in a database query language (e.g., SQL (structured querylanguage), an OQL (object query language), a natural language, and soon.

“Signal”, as used herein, includes but is not limited to, electricalsignals, optical signals, analog signals, digital signals, data,computer instructions, processor instructions, messages, a bit, a bitstream, or other means that can be received, transmitted and/ordetected.

“Software”, as used herein, includes but is not limited to, one or moreexecutable instruction that cause a computer, processor, or otherelectronic device to perform functions, actions and/or behave in adesired manner. “Software” does not refer to stored instructions beingclaimed as stored instructions per se (e.g., a program listing). Theinstructions may be embodied in various forms including routines,algorithms, modules, methods, threads, and/or programs includingseparate applications or code from dynamically linked libraries.

“User”, as used herein, includes but is not limited to one or morepersons, software, computers or other devices, or combinations of these.

Some portions of the detailed descriptions that follow are presented interms of algorithms and symbolic representations of operations on databits within a memory. These algorithmic descriptions and representationsare used by those skilled in the art to convey the substance of theirwork to others. An algorithm, here and generally, is conceived to be asequence of operations that produce a result. The operations may includephysical manipulations of physical quantities. Usually, though notnecessarily, the physical quantities take the form of electrical ormagnetic signals capable of being stored, transferred, combined,compared, and otherwise manipulated in a logic, and so on. The physicalmanipulations create a concrete, tangible, useful, real-world result.

It has proven convenient at times, principally for reasons of commonusage, to refer to these signals as bits, values, elements, symbols,characters, terms, numbers, and so on. It should be borne in mind,however, that these and similar terms are to be associated with theappropriate physical quantities and are merely convenient labels appliedto these quantities. Unless specifically stated otherwise, it isappreciated that throughout the description, terms including processing,computing, determining, and so on, refer to actions and processes of acomputer system, logic, processor, or similar electronic device thatmanipulates and transforms data represented as physical (electronic)quantities.

FIG. 1A is a functional block diagram that outlines one exampleembodiment of an entailment process 100. An inference engine 110 is usedto fire a set of inference rules 150 on triples in a semantic data modelto create inferred triples. The entailment outlined in FIG. 1 reflects aforward-chaining strategy. The inference process starts with thecreation of a new partition in a triple table 140 that stores amaterialized view of the subject (SID), property (PID), and object (OID)components of triples in the data model. The new partition willultimately store the inferred graph (set of inferred triples) thatresults from the entailment process. A temporary table 120 is alsocreated by the inference engine 110. Like the triple table 140, thetemporary table has three columns, SID, PID, OID that together store atriple. The temporary table 120 is typically partitioned on the PID(triple predicate). When ancillary information is to be generated byentailment, the temporary table may have additional DISTANCE or PROOFcolumns.

The core inference logic is driven by the set of inference rules 150.Conceptually, each rule will be executed (fired) during inference andonly new (previously nonexistent) triples are added into the temporarytable. The rules are initially executed on a semantic model table (notshown) that holds data for one or more semantic models. The semanticmodel table is typically partitioned on a model identifier. To execute arule, matched triples of each antecedent are located and joined based oncommon variables to produce corresponding consequent triples. Forexample, a rule that specifies that if a class U is a subclass of X anda resource V of type U, then V is also of type X would be expressed aspart of a semantic model in OWL as follows:

U rdfs:subClassOf X. V rdf:type U → V rdf:type XA translation of this rule into SQL would be as follows. The presence oftwo antecedent patterns translates into a 2-way self-join on <IVIEW>,which is an inline view representing the union of triples in thesemantic model and newly inferred triples in the temporary table 120.The single common variable U that connects the two triple patterns inthe antecedent provides the join condition T1.SID=T2.OID. The NOT EXISTSclause filters out triples already present in <IVIEW>.

select distinct T2.SID sid, ID(rdf:type) pid, T1.OID oid from <IVIEW>T1, <IVIEW> T2 where T1.PID = ID(rdfs:subClassOf) and T2.PID =ID(rdf:type) and T1.SID = T2.OID and NOT EXISTS (select 1 from <IVIEW> mwhere m.SID = T2.SID and m.PID = ID(rdf:type) and m.OID = T1.OID)

The SELECT list is formed based upon the triple pattern in theconsequent of the rule. The triples returned by the SELECT statement areinserted using an INSERT AS SELECT into the temporary table. Note thatthe ID( ) function invocations will be replaced with the actual integerIDs to avoid execution time overhead.

In one pass, all rules will be examined; and if no rule generates anynew triples, the inference process terminates. All triples from thetemporary table 120 are copied into an exchange table 130 that hasexactly the same structure as the triple table 140. The exchange tableis indexed and exchanged into the newly created partition in the tripletable 140. The exchange operation is a virtually zero-time operationbecause it involves only updating metadata of the tables.

FIG. 1B is a functional block diagram that outlines an adaptation of theentailment process shown in FIG. 1A. In the entailment process 160 shownin FIG. 1B, each of the n inference rules 185 is broken into componentsthat are executed in parallel. As with the system outlined in FIG. 1A,an inference engine 170 is used to fire the inference rules 185 ontriples in a semantic data table (not shown), which is partitioned onmodel identifier, to create inferred triples. The inference processstarts with the creation of a new partition in a triple table 190 thatstores a materialized view of the subject (SID), property (PID), andobject (OID) components of triples in the data model. The new partitionwill ultimately store the inferred graph (set of inferred triples) thatresults from the entailment process. A temporary table 175, which ispartitioned on triple predicate, is also created by the inference engine160. Like the triple table 190, the temporary table has three columns,SID, PID, OID that together represent a triple.

The set of inference rules are executed on the semantic data model tableby executing the component inference rules for each inference rule inparallel. In one pass, all rules will be examined; and if no rulegenerates any new triples, the inference process terminates. All triplesfrom the temporary table 120 are copied into an exchange table 130 thathas exactly the same structure as the triple table 140. The exchangetable is indexed and exchanged into the newly created partition in thetriple table 140. Surprisingly, simply executing the inference rules inparallel on data in the semantic data model has not been shown toprovide the improved performance that would be expected. Storing thetriples from the semantic model in a data source that is adapted forparallel inference and executing the inference rules, in parallel, onthe data source (rather than the semantic model table) may improveperformance during entailment.

FIG. 2 illustrates an example embodiment of a computing system 200 thatperforms entailment on triples associated with number m of semanticmodels and stored in a model table 210. The model table 210 ispartitioned on a semantic model identifier. The system 200 includes aninference data source logic 220 that creates a source table 230 to storethe triples in a manner that is adapted for parallel inference. Ofcourse, it will be appreciated that the source table 230 may also beused with systems that perform serial inference.

The source table 230 is partitioned on triple predicate and as such hasone partition for each of n predicates. In a typical semantic model, thenumber of unique predicates is much smaller than the number of uniquesubjects/objects. In one example embodiment, the inference data sourcelogic 220 creates the source table 230 using hash partitioning asfollows.

create table<source_table_name> (predicate_id, object_id, subject_id)partition by hash(predicate_id) as select * from ( select predicate_id,object_id, subject_id from <MODEL1> UNION ALL select predicate_id,object_id, subject_id from <MODEL2> UNION ALL.... select predicate_id,object_id, subject_id from <MODELm> );List partitioning may be used if the set of predicates is known at thetime of source table creation. An inference engine 240 executesinference rules in parallel on the source table 230 to performentailment of the semantic model. Inferred triples are stored in atemporary table 250, which is also partitioned on triple predicate.

Example methods may be better appreciated with reference to flowdiagrams. While for purposes of simplicity of explanation, theillustrated methodologies are shown and described as a series of blocks,it is to be appreciated that the methodologies are not limited by theorder of the blocks, as some blocks can occur in different orders and/orconcurrently with other blocks from that shown and described. Moreover,less than all the illustrated blocks may be required to implement anexample methodology. Blocks may be combined or separated into multiplecomponents. Furthermore, additional and/or alternative methodologies canemploy additional, not illustrated blocks.

FIG. 3 illustrates an example embodiment of a method 300 that creates asource table that is adapted for parallel inference. At 310, an emptysource table is created that includes columns for a triple predicateidentifier (PID), a triple object identifier (OID), and a triple subjectidentifier (SID). The source table is partitioned on predicateidentifier. At 320, the method performs a selection of all the triplesfrom all the relevant semantic models in the model table.

While FIG. 3 illustrates various actions occurring in serial, it is tobe appreciated that various actions illustrated in FIG. 3 could occursubstantially in parallel. By way of illustration, a first process couldcreate an empty source table and a second process could populate thesource table. While two processes are described, it is to be appreciatedthat a greater and/or lesser number of processes could be employed andthat lightweight processes, regular processes, threads, and otherapproaches could be employed.

FIG. 4 illustrates an example embodiment of a computing system 400 thatperforms entailment on triples associated with number m of semanticmodels and stored in a model table 410. The model table 410 includescolumns that store identifiers of triple components. To provide a morecompact data source for parallel inference the system includes ainference data source logic 420 that maps triple identifiers from themodel table 410 to compact identifiers that require less storage andstores the compact identifiers in a source table 430. An inferenceengine 440 executes inference rules in parallel on the source table 430to perform entailment of the semantic model. Inferred triples are storedin a temporary table 450, which also stores compact identifiers. Usingmore compact identifiers reduces the amount of space needed to store andmanipulate triples, improving performance during parallel inference. Ofcourse, it will be appreciated that the compact identifiers may also beused with systems that perform serial inference.

In one example embodiment, the compact identifier logic sets the columntype for the source table to an 8-byte binary RAW type that is largeenough to hold hashed component identifiers. The URIs, literals, andblank nodes in the model table 410 may be hashed into 8 byte integer IDsfor storage in the temporary table (175 in FIG. 2) and triple table (190in FIG. 2). However, the mapped integer IDs tend to be sparse so that,even with this improvement, the temporary table and triple table maystill consume more memory than necessary.

In another example embodiment, the compact identifier logic sequentiallymaps the triple component identifiers to a compact identifier comprisinga unique integer value. Perfect reverse hashing is one way tosequentially map the triple component identifiers to compactidentifiers. The inference data source logic determines a minimum columnwidth necessary to store a largest of the compact identifiers and storesthe compact identifiers in a source table having the determined columnwidth, thereby minimizing the size of the source table.

FIG. 5 illustrates an example embodiment of a method 500 that generatescompact identifiers for triple component identifiers stored in asemantic model table. At 510 the triple component identifiers are input.At 520, the component identifiers are mapped to compact identifiers. Themapping performed at 520 may include sequentially mapping the triplecomponent identifiers to a compact identifier comprising a uniqueinteger value. At 530 a column size is determined for the source tablebased on a number of bytes necessary to store a largest of the compactidentifiers.

While FIG. 5 illustrates various actions occurring in serial, it is tobe appreciated that various actions illustrated in FIG. 5 could occursubstantially in parallel. By way of illustration, a first process couldmap the component identifiers to compact identifiers and another processcould create an empty source table have the proper column width. Whiletwo processes are described, it is to be appreciated that a greaterand/or lesser number of processes could be employed and that lightweightprocesses, regular processes, threads, and other approaches could beemployed.

In one example, a method may be implemented as computer executableinstructions. Thus, in one example, a computer-readable medium may storecomputer executable instructions that if executed by a machine (e.g.,processor) cause the machine to perform a method that includes accessinga set of triples and inference rules associated with a semantic model;creating a source table that is adapted for parallel inference to storethe set of triples for entailment; storing the set of triples in a thesource table; firing the inference rules in parallel on the triples inthe source table to generate inferred triples associated with thesemantic model. While executable instructions associated with the abovemethod are described as being stored on a computer-readable medium, itis to be appreciated that executable instructions associated with otherexample methods described herein may also be stored on acomputer-readable medium.

FIG. 6 illustrates an example computing device in which example systemsand methods described herein, and equivalents, may operate. The examplecomputing device may be a computer 600 that includes a processor 602, amemory 604, and input/output ports 610 operably connected by a bus 608.In one example, the computer 600 may include a data source logic 630configured to facilitate incremental inference. In different examples,the logic 630 may be implemented in hardware, software stored ascomputer executable instructions on a computer-readable medium,firmware, and/or combinations thereof. While the logic 630 isillustrated as a hardware component attached to the bus 608, it is to beappreciated that in one example, the logic 630 could be implemented inthe processor 602.

Thus, logic 630 may provide means (e.g., hardware, software stored ascomputer executable instructions on a computer-readable medium,firmware) for storing at least one semantic model comprising one or moreinference rules and a set of triples associated with the model; means(e.g., hardware, software stored as computer executable instructions ona computer-readable medium, firmware) for creating a data source thatstores the triples in a manner adapted for parallel inference; and means(e.g., hardware, software stored as computer executable instructions ona computer-readable medium, firmware) for firing the inference rules, inparallel, on the data source to create inferred triples associated withthe semantic model.

The means may be implemented, for example, as an ASIC (applicationspecific integrated circuit) programmed to apply a hybrid approach toequivalence reasoning. The means may also be implemented as computerexecutable instructions that are presented to computer 600 as data 616that are temporarily stored in memory 604 and then executed by processor602.

Generally describing an example configuration of the computer 600, theprocessor 602 may be a variety of various processors including dualmicroprocessor and other multi-processor architectures. A memory 604 mayinclude volatile memory and/or non-volatile memory. Non-volatile memorymay include, for example, ROM (read only memory), PROM (programmableROM), and so on. Volatile memory may include, for example, RAM (randomaccess memory), SRAM (synchronous RAM), DRAM (dynamic RAM), and so on.

A disk 606 may be operably connected to the computer 600 via, forexample, an input/output interface (e.g., card, device) 618 and aninput/output port 610. The disk 606 may be, for example, a magnetic diskdrive, a solid state disk drive, a floppy disk drive, a tape drive, aZip drive, a flash memory card, a memory stick, and so on. Furthermore,the disk 606 may be a CD-ROM (compact disk) drive, a CD-R (CDrecordable) drive, a CD-RW (CD rewriteable) drive, a DVD (digitalversatile disk and/or digital video disk) ROM, and so on. The memory 604can store a process 614 and/or a data 616, for example. The disk 606and/or the memory 604 can store an operating system that controls andallocates resources of the computer 600.

The bus 608 may be a single internal bus interconnect architectureand/or other bus or mesh architectures. While a single bus isillustrated, it is to be appreciated that the computer 600 maycommunicate with various devices, logics, and peripherals using otherbusses (e.g., PCI (peripheral component interconnect), PCIE (PCIexpress), 1394, USB (universal serial bus), Ethernet). The bus 608 canbe types including, for example, a memory bus, a memory controller, aperipheral bus, an external bus, a crossbar switch, and/or a local bus.

The computer 600 may interact with input/output devices via the i/ointerfaces 618 and the input/output ports 610. Input/output devices maybe, for example, a keyboard, a microphone, a pointing and selectiondevice, cameras, video cards, displays, the disk 606, the networkdevices 620, and so on. The input/output ports 610 may include, forexample, serial ports, parallel ports, and USB ports.

The computer 600 can operate in a network environment and thus may beconnected to the network devices 620 via the i/o interfaces 618, and/orthe i/o ports 610. Through the network devices 620, the computer 600 mayinteract with a network. Through the network, the computer 600 may belogically connected to remote computers. Networks with which thecomputer 600 may interact include, but are not limited to, a LAN (localarea network), a WAN (wide area network), and other networks.

While example systems, methods, and so on have been illustrated bydescribing examples, and while the examples have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. It is, of course, not possible to describe every conceivablecombination of components or methodologies for purposes of describingthe systems, methods, and so on described herein. Therefore, theinvention is not limited to the specific details, the representativeapparatus, and illustrative examples shown and described. Thus, thisapplication is intended to embrace alterations, modifications, andvariations that fall within the scope of the appended claims.

To the extent that the term “includes” or “including” is employed in thedetailed description or the claims, it is intended to be inclusive in amanner similar to the term “comprising” as that term is interpreted whenemployed as a transitional word in a claim.

To the extent that the term “or” is employed in the detailed descriptionor claims (e.g., A or B) it is intended to mean “A or B or both”. Whenthe applicants intend to indicate “only A or B but not both” then theterm “only A or B but not both” will be employed. Thus, use of the term“or” herein is the inclusive, and not the exclusive use. See, Bryan A.Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed. 1995).

1. A computer-implemented method, comprising: accessing a set of triplesand inference rules associated with a semantic model; storing the set oftriples in a data source adapted for parallel inference; and providingthe data source to an inference engine that fires the inference rules inparallel on the triples in the source table to generate inferred triplesassociated with the semantic model.
 2. The computer-implemented methodof claim 1 where the triples comprise a triple predicate and wherestoring of the set of triples in the data source is performed by storingthe triples in a source table that is partitioned on triple predicate.3. The computer-implemented method of claim 2 where the source table iscreated by performing a union of selection operations on all triplesassociated with one or more semantic models.
 4. The computer-implementedmethod of claim 3 where the source table is partitioned by a predicateidentifier.
 5. The computer-implemented method of claim 1 where thestoring of triples in the data source is performed by mapping triplecomponent identifiers associated with triples in the set of triples to aset of compact identifiers that require less storage space than a triplecomponent identifier in the set of triples that requires the moststorage space and storing the compact identifiers in the data source. 6.The computer-implemented method of claim 5 where the mapping isperformed by sequentially mapping the triple component identifiers to acompact identifier comprising a unique integer value.
 7. Thecomputer-implemented method of claim 5 comprising determining a minimumcolumn width necessary to store a largest of the compact identifiers andstoring the compact identifiers in a source table having the determinedcolumn width.
 8. The computer-implemented method of claim 5 where themapping is performed by using perfect reverse hashing to map hashedtriple component identifiers to a sequential set of integer values.
 9. Acomputing system comprising: data storage that stores at least onesemantic model comprising one or more inference rules and a set oftriples associated with the model; an inference data source logic thatcreates a data source that stores the triples in a manner adapted forparallel inference; and an inference engine that fires the inferencerules, in parallel, on the data source to create inferred triplesassociated with the semantic model.
 10. The computing system of claim 9where the inference data source logic creates a source table and storesthe triples in the source table partitioned on triple predicate.
 11. Thecomputing system of claim 10 where the inference data source logiccreates the source table by performing a query on one or more semanticmodels that selects all triples associated with the one or more semanticmodels and performing a union operation on the returned triples.
 12. Thecomputing system of claim 9 where the inference data source logiccreates a data source adapted for parallel inference by mapping triplecomponent identifiers for the triples associated with the semantic modelto a set of compact identifiers that require less storage space than atriple component identifier in the set of triples that requires the moststorage space and storing the compact identifiers in the data source.13. The computing system of claim 12 where inference data source logicsequentially maps the triple component identifiers to a compactidentifier comprising a unique integer value.
 14. The computing systemof claim 12 where the inference data source logic determines a minimumcolumn width necessary to store a largest of the compact identifiers andstores the compact identifiers in a source table having the determinedcolumn width.
 15. A computer-readable medium storing computer executableinstructions that when executed by a computer cause the computer toperform a method, the method comprising: accessing a set of triples andinference rules associated with a semantic model, where a tripleincludes a predicate component; creating a source table to store the setof triples for entailment, where the source table is adapted forparallel inference; storing the set of triples in the source table; andfiring the inference rules in parallel on the triples in the sourcetable to generate inferred triples associated with the semantic model.16. The computer-readable medium of claim 15 where the source table ispartitioned on triple predicate.
 17. The computer-readable medium ofclaim 15, the instructions comprising performing a union of selectionoperations on all triples associated with one or more semantic models tocreate the source table.
 18. The computer-readable medium of claim 15,the instructions comprising sequentially mapping triple componentidentifiers associated with the triples to a compact identifiercomprising a unique integer value.
 19. The computer-readable medium ofclaim 18, the instructions comprising determining a minimum column widthnecessary to store a largest of the compact identifiers and creating asource table having the determined column width.
 20. A system,comprising: means for storing at least one semantic model comprising oneor more inference rules and a set of triples associated with the model;means for creating a data source that stores the triples in a manneradapted for parallel inference; and means for firing the inferencerules, in parallel, on the data source to create inferred triplesassociated with the semantic model.